It is known to access multiple locations on a sample. (eg. during mapping procedures), using Reflectometer, Spectrophotometer and Ellipsometer systems. See for instance, U.S. Pat. Nos. 8,436,994, 7,872,751, 8,248,606, and 8,339,603 to Liphardt et al., U.S. Pat. Nos. 7,505,134, 7,746,471 and 7,746,472 to Johs et al., U.S. Pat. Nos. 8,059,276, 8,570,513 to Hilfiker et al., U.S. Pat. No. 9,933,357 to He et al., U.S. Pat. No. 8,248,607 to Herzinger et al. and U.S. Pat. No. 9,347,768 to Pfeiffer et al.
The most direct approach to accomplishing sample mapping applies two translation elements each comprising a fixed part and a translatable part such that linear translation can be affected between said fixed and translatable parts along a given axis within each element. The fixed part of the second translation element is attached to the translatable part of the first element, with the translation axis of the second element not parallel to that of the first. Ideally, the translation axes of the two elements are roughly perpendicular. A stage for supporting a sample is affixed to said translatable part of said second translation element. In use, the translatable parts of each translation element are caused to linearly translate along their respective axes, allowing a beam to access substantially any location on a sample placed on said stage. Such a mapping system is commonly referred to as an X-Y translation system. Another approach involves a translation element comprising a fixed part and a translatable part and a rotation element comprising a fixed part and a rotatable part, such that in use rotation between said fixed part and said rotatable part can be affected. The fixed part of the rotation element is attached to the translatable part of the first element, with the translation axis of the first element oriented perpendicular to the rotation axis of the second element. A stage for supporting a sample is affixed to said rotatable part of said rotation element. In use the translatable part of the translation element is caused to linearly translate with respect to the fixed element, and the rotatable part of the rotation element is caused to rotate with respect to the fixed element, allowing a beam to access substantially any location on a sample placed on said stage. Such a mapping system is commonly referred to as an R-Theta translation system.
In order to map a circular sample with radius R using the first approach, each translation element must have a linear range of at least 2R and the footprint of the sample translation is approximately 4R by 4R.
With the second approach, the rotation element can rotate to substantially any angle, and the necessary range of translation is reduced to 1R. The footprint of sample translation is approximately 3R×2R, resulting in a more compact system.
Another approach provides that a first rotatable element is secured at a first fixed part, and a second rotatable element is secured at a second fixed element, which can be visualized as a like an old record player.
Summarizing, Metrology systems used in sample mapping can comprise a first element allows motion in, say an “X” direction, and the second in a “Y” direction. The second element is slidably affixed to the first element, and has a sample supporting stage slidably affixed thereto. In use specific “X”-“Y” positions on a sample which is placed on the stage can be accessed by an electromagnetic beam by slidably moving the second element with respect to the first, and by slidably moving the stage with respect to the first element. Another approach involves a first element to which is slidably affixed a second element, which second element has a stage for supporting a sample rotatably affixed thereto. In use the second element is slid to a location with respect to the first element, and then the stage is rotated to provide access to specific locations on a sample placed on the stage. The first approach requires a system which is as wide as it is deep to allow both “X” and “Y” motions. The second approach can be implemented by a system than needs only about half the width, (ie. the required travel range of the stage is only the radius of the sample stage). Another approach, which again provides a compact system, can be envisioned as being similar to an old record player. A first element is rotatably affixed to a support, as is a second element to which is attached a stage for supporting a sample. The second element is rotatably affixed at distance from the point at which the first element is rotatably affixed. In use the first element is rotated about the position at which it is rotatably affixed to the support so that a distal end thereof is positioned adjacent to a sample which is placed on said stage, and said stage is rotated about the position at which it is rotatably attached. Again, specific locations on a sample can be accessed by an electromagnetic beam.
Even in view of the foregoing, need remains for improved compact systems which allow accessing specific locations on a sample, and thereby allow mapping samples by Reflectometer, Spectrophotometer and Ellipsometer systems.